19 7月 Aluminium Refining Process
Aluminium Refining Process
Aluminium Refining Process- Electrolytic Process
In this process the oxygen in the alumina reacts with the carbon anodes and cathodes forming CO2 and aluminum.
The alumina is conveyed from the storage silos and fed into an ore bin centrally located over the cell.
The bin then supplies the cell with alumina as required.
Cryolite powder (sodium fluoride) and alumina are loaded into the cell.
A low voltage, high amperage DC electrical current is applied to the anode bus bar from where it is transmitted to the anode block, while the aluminum smelting DC bus temperature monitoring is carried out in the control room.
The current passes from the anode block, through the mix of cryolite and alumina into the cathode, and in the process the alumina is reduced, becoming molten aluminum.
The molten aluminum drops to the bottom of the cell from where it is removed by a siphon into a crucible and transported in its molten state to the cast house to undergo the next process.
Aluminium Refining Process– Casting of Aluminum
The molten aluminum in the crucible is poured into a reverberatory furnace, usually located in the cast house section of the smelter.
This is a simple furnace consisting of a steel box lined with firebricks internally and externally, having two or three gas burners inset to the side walls.
There is a loading door on the front, which can be lowered and raised as required and a tapping point at the rear to allow the metal to be supplied to the casting equipment.
The furnace temperature is held a little above 600C while samples of the molten aluminum are taken to evaluate the metal’s properties. Any necessary measures are taken to remove impurities.
Once the required purity is achieved, the furnace is tapped and the molten aluminum cast into ingots, billet, or rectangular blocks depending on the clients requirements.
The billets and blocks are then cut to standard sizes, stamped with the cast details, and palleted for transportation to the various aluminum extruding facilities.
An example of a reverberatory furnace is shown below.